Rubber O-rings are one of the smallest components in a conveyor system, and also one of the easiest to overlook — until one fails. Sitting inside idler and drive rollers, these simple loops of rubber quietly absorb shock, transmit drive, and keep rollers turning smoothly for millions of cycles. This guide covers what O-rings are made of, how they're sized, where they're used on a roller conveyor, and how to choose the right one for your application.
What is a rubber O-ring?
An O-ring is a torus-shaped ring of elastomer, defined by two measurements: its inner diameter (ID) and its cross-sectional thickness (CS). On a conveyor roller, O-rings are typically fitted into a machined groove on the roller shell or used as a drive belt between adjacent rollers, transferring rotation from a powered roller to idle ones without a chain or motorized roller at every position.
Common materials
Material choice depends on load, speed, temperature, and the environment the conveyor operates in:
- Nitrile (NBR) — the most common choice for general material handling; good abrasion resistance and a reasonable cost.
- EPDM — better resistance to heat, ozone, and outdoor weathering, often used on rooftop or outdoor conveyor lines.
- Polyurethane — higher load capacity and longer wear life, favoured in high-cycle sortation and distribution centre applications.
- Silicone — used sparingly, mainly where food-grade or high-temperature properties are required.
Where O-rings are used on a roller conveyor
The two most common applications are drive transmission and cushioning:
- O-ring drive — a ring stretched between the drive groove of a powered roller and the groove of the next idle roller, so rotation passes down the line roller to roller.
- Shock and vibration damping — O-rings seated at the roller-to-frame interface reduce noise and cushion impact when heavier loads are transferred onto the conveyor.
A correctly sized O-ring should sit under light tension when installed — enough to maintain positive drive contact without over-stressing the rubber or the roller bearings.
How to choose the right O-ring
Getting the size and material right up front avoids premature wear and unplanned downtime. A few practical guidelines:
- Measure the groove diameter on the roller, not just the roller's outer diameter.
- Match cross-section thickness to the groove width — an undersized ring will slip, an oversized one will overheat.
- Account for the conveyor's duty cycle: continuous high-speed lines wear rings faster than intermittent-use lines.
- Consider the operating environment — oils, UV exposure, and temperature swings all shorten the service life of the wrong material.
Signs an O-ring needs replacing
Watch for slipping or skipped rollers under load, visible cracking or flat spots on the ring, and unusual squealing near the drive groove. Because O-rings are inexpensive relative to roller downtime, most operations keep a stock of common sizes on hand for quick replacement during scheduled maintenance.
At Flexitech Engineering, every roller we manufacture is built to accept standard O-ring drive sizes, and we stock nitrile, EPDM, and polyurethane rings across our common roller diameters — so replacements are a shelf item, not a special order.
